Three legged staple



Oct. 29, 1957 H. KLOPSTOCK THREE LEGGED STAPLE Filed March 16, 1955 M m 0 W. T of T S Q A P 9 E 1 2,s11,073 r THREE LEGGED STAPLE 2 Application March .16, 1 955, Serial No. 494,747

Claims priority, application Great Britain October 31, 1950 7 Claims. cl. 851-49) The present invention relates to staples, and more particularly to staples of the kind that are forced or .driven into Wood and similar material bymeans of a stapling machine or gun.

, Heavy duty staplesof the aforesaid kind are widely used, for instance, in the furniture and upholstery fields. They are also'frequently used for such purposes as binding the edges of boxes and crates. In contrast to staples used to staple together several sheets of paper 'or'other easily pierceable material and relying for anchorage primarily upon bending over the protruding portions of the staple legs, heavy duty staples of the generalikind above referred to, must penetrate into comparatively hard material with the full length of the legs and rely for anchorage upon the areas of contact between the legs and the penetrated material. Furthermore, the use to which staples of the kind here involved are put demands on one hand that the stapled' material such as fabric is strongly secured to its support such as a furniture frame, or in other words, that the ipull-out forcenecessary to pull the'staple out of the wood or other materialis-compar'atively high. oh the other hand, the material from whichthe s taples are made must be light for reasons of economy,,,to permit stapling with a simple hand operated stapling machine and to make the staples inconspicuous..

Accordingly, the principal object of the present invention is to provide a novel and improved staple of the general type above referred to, which can be readily forced or driven into comparatively hard material such as wood and'which due to its design is strongly retained in the material.

;.Another object of the invention is to provide a novel and improved staple design which combines excellent holding properties with strength so that the legs of a staple made of comparatively thin wire can be driven with the full length of the staple legs into the material without danger of crumbling of the legs.

'7 Still another object of the invention is to provide a novel and improved staple which is so designed that when the staple is driven into the material the staple legs experience deformation such that the strength of the anchorage of the staple within the material is materially increased, or more specifically that the legs are keyed into the material.

Other and further objects, features and advantages of the invention will be pointed out hereinafter and set forth in the appended claims forming part of the invention.

The present application is a continuation-in-part of my co-pending application Ser. No. 252,641, filed October 23, 1951.

In the accompanying drawing a preferred embodiment of the invention is shown by way of illustration and not by way of limitation.

In the drawings:

Fig. 1 is an elevational side view of a staple according to the invention.

Fig. 2 is a section of wood and fabric material stapled together by a staple as shown in Fig. l, and

tate Pa o Fig.3 is a bank of staples as shown in Fig. 1 for use in a stapling machine or gun.

.Referring to Fig. l of the drawing, the staple as exexemplified in this figure is formed from a single length of metal 'wire, the term wire as herein used being intended to include also a narrow metal strip. 1

The stapleas shown has three substantially parallel legs 1, 2 and 3, preferably equally spaced, The three legs are of the same length and lie at right anglesto connecting crown or top parts 4 and 5. The two outer legs are formed by a single thickness of a bent-off wire portion. The intermediate or central leg 2 is of double thickness of wire resulting from doubling up the wire. The wire portions 2' and 2" are so bent that they form two continuous shanks of equal length and a shallow loop or bulbous portion the widest portion of which is at the tip of the leg and which is closed toward the base of the leg where it joins top parts 4- and 5. The outer legs 1 and 3 may be pointed at tips 1' and 3 respectively whereas the tip of leg 2 is left blunt. A point having an angle of 90 has been found suitable.

As is evident, central leg 2 is of greater strength than outer legs 1 and 3, it has a larger area of contact than the outer legs and it presents more resistance to being driven into material than the outer legs. ,The purpose of these difierences between the outer legs and the central leg will become apparent from the subsequent'description.

Staples according to Fig. 1 may be produced by cutting a suitable length of wire from a supplyreel of such wire.

v The subsequent cutting and bending operations generally provide edges at the tips of the outer legs that are sufliciently sharp to permit the staples to be forced into Wood or other material by a staple machine or gun. However,

for some applications, it may be desirable additionally tosharpen the tips of the outerlegs. The tip ofthe central leg is always left blunt. t

V Themanufacture of the staples will present no diffi culty to those skilled in the art. For example, with a required length of wire, a forming blade may descend centrally on the length to bendthe central part thereofso as to form the double thickness leg 2. Simultaneously or subsequently the ends of the length are bent outwardly. by known means to form legs "1 and 3.

When manufactured for use in staple machine s, staples are glued or frozen together side by side for example; with an adhesive in customary manner to' form a bank" of staples as shown in Fig. 3 that can be fed into a stapling machine for single ejection from the machine into the place of application.

Stapling machines or guns suitable for staples according to the invention are described in my co-pendi'ng application Ser. No. 238,688, filed July 25, 1951.

Let it now be assumed that a staple as shown in Fig. 1 is driven by a suitable'stapling machine into a wooden block or bar 6 which may be visualized as part of a fur-f niture frame for stapling thereto two fabric layers 7 and 8'.'

The stapling machine will exert a substantially uniform pressure upon the entire crown or top bar 4, 5 of the staple. Legs 1 and 3 consisting of a single more or less pointed length of wire offer less resistance to penetration into the wood than leg 2 being made of a double length of wire and having a blunt tip. The base or root of leg 2 constitutes in effect a fulcrum for two levers formed by parts 4 and 5 and legs 1 and 3 depending therefrom. As a result, legs 1 and 3 tend to be turned slightly inwardly and the loop of leg 2 is slightly widened, particularly near the tip of the leg. Fig. 2 clearly shows the positions actually occupied by the legs of a staple driven into wood. It will be noted that the lower part of the loop of leg 2 remains wider than the part of the loop facing the base of the leg. Nevertheless, the leg remains in tight frictional contact with the surrounding wood along its entire length due to the self-sealing properties of wood and similar material.

Itis further apparent frornFig. 2 that the: staple is retained Within the wood not merely by the frictional, contact between the staple legs'and the wood" but is. positively keyed or dovetailed into the/wood. Obviously, the keying action materially increases the strength of adhesion'of the staple within the woods, or in ofher words, theeffectiven'ess of the staple. v v Whatisclair'rieiist, 1. A heavyduty staple for use in stapling machines, comprising a length of wire of uniform thickness throughout its length, said wire forming three depending, legs joined by wire portions disposed -at' a substantially "right angle with the legs, two of said legs being in the form ofa single wire portion at each end of the wire and the third leg beingdisposed intermediate the end legs and in the form of a'doubled-up wire portion comprising two substantially straight parallel shanks contiguous throughout their length and of equal length but curved at the tip of the leg outwardly in the longitudinal plane of the staple to define a bulbous tip portion having an outer width in that plane in excess of the combined cross-sectional width of said straight shanks.

2. A heavy duty staple for use in stapling machines, comprising a length of wire of uniform thickness throughout its length, said wire forming three depending legs angle with the legs, two of said legs being in the form of a single wire portion at each end of the wire and the third leg being disposed intermediate the end legs and in the form of a doubled-up wire portion, said doubled-up wire portion comprising two substantially straight parallel shanks depending from said joining wire portions contiguous throughout their length and of equal length but spread apart at the tip end of the third leg to form a bulbous configuration laterally extending in the longitudinal plane of the staple.

5. A heavy duty staple for use in stapling machines, comprising a length of wire of uniform thickness throughout its length, said .wire forming three depending legs joined by wire portions disposed at a substantially right joined by wire portions disposed at a substantially right angle with the legs, two of said legs being in the form of a single wire portion at each end of the wire and the third leg being disposed intermediate the end legs and in the form of a doubled-up wire portion comprising two substantially straight parallel shanks contiguous throughout their length and of equal length but curved at the tip of the leg outwardly in the longitudinal plane of the staple to define a bulbous tip portion having an. outer width in that plane in excess of the combined crosssectional width of said straight shanks, said outer legs having pointed tips and the bulbous tip of. the intermejoined by wire portions disposed at a substantially right angle with the legs, two of said legs being in the form of a single Wire portion at each end of the wire and the third leg being disposed intermediate the end legsv and in the form of a doubled-up wire portion comprising two substantially straight parallel shanks contiguous throughout their length and of equal length but curved at the tip of the leg outwardly in the longitudinal plane of the staple to define a bulbous tip portion having an outer width in that plane in excess of the combined cross-sectional width of said straight shanks, said three legs being of substantially equal length.

4. A heavy'duty staple for use in stapling machines, comprising a length of wire of uniform thickness throughout its length, said wire forming three depending legs joined by wire portions disposed at a substantially right angle with the legs, two of said legs being in the form of a single wire portion ateach end of the wire and the third leg being disposed intermediate the end legs and in the form of a doubled-up wire portion, said doubled-up wire portion comprising two substantially straight parallel shanks depending from said joining wire portions con tiguous throughout their length and of equal length but spread apart at the tip end of the third leg to form a bulbous configuration laterally extending in the longitudinal plane of the staple, said three legs being of substantially equal length. I

6. A heavy duty staple for use in stapling machines, comprising a length of wire of uniform thickness throughout its length, said wire forming three depending legs joined by wire portions disposed at a substantially right angle with the legs, two of said legs being in the form of a single wire portion at each end of the wire and the thirdleg being disposed intermediate the end legs and in the form of a doubled-up wire portion, said doubled-up wire' portion comprising two substantially straight parallel shanks depending from said joining wire portions contiguous throughout their length and of equal length but spread apart at the tip end of the third leg to form 'a' bulbous configuration laterally extending in the Iongitudinal plane of the staple, said three legs being of substantially equal length, the two outer legs having pointed tips and the intermediate leg having a blunt tip relative'to said tip end to form a bulbous tip, all three legs being oil equal length and disposed in parallel relationship.

References Cited in the file of this patent UNITED STATES PATENTS 210,482 Andren Dec. 3, 1878 484,107 Miller Oct. 11, 1892. 777,453 Wakefield Dec. 13, 1904- 1,6S4,37l Goodstein Dec. 27, 1927 

